79 
on which the action of the heart depends , &c. 
after the brain is wholly removed, and its powers seem not 
at all immediately impaired by the removal of the brain; yet 
we constantly see injuries of the brain impairing the functions 
of the spinal marrow. We may wholly remove the brain, 
and the animal performs the various motions of its limbs as 
well as before its removal. Yet an injury of the brain often 
produces complete haemiplegia, nay often instantly destroys 
every function of the system. Of this apparent inconsistency, 
M. le Gallois justly remarks, that two facts well ascertained, 
however inconsistent they may seem, do not overturn each 
other, but only prove the imperfection of our knowledge. 
Whichever of the disputed opinions respecting the func- 
tions of the nervous system we adopt, the foregoing pheno- 
mena seem to imply a contradiction; for an explanation of 
them, therefore, we must recur to principles different from 
those hitherto assumed. The following experiments point 
out still another instance of this apparent contradiction, and 
seem to suggest the principle on which the whole depends. 
Exp. 18. By applying strong stimuli to the spinal marrow 
of a frog, strong and repeated contractions were excited in 
the muscles of the hind limbs, as long as the stimuli would 
produce the effect. On examining the state of the muscles 
of these limbs, I found them wholly deprived of their excita- 
bility. Now it is well known, that although all the nerves 
supplying the limbs of a frog be divided, and cut out close to 
the place where they enter the muscles, the latter still retain 
their excitability, which appears to be not at all less than 
while the nerves are entire. Lest it may be supposed that 
the nervous influence, which was exhausted in this experi- 
ment by stimulating the spinal marrow, still remains in 
